Steam generator for domestic household appliance

ABSTRACT

A household appliance includes a housing having a door formed in a front panel thereof for accessing an interior of the housing, a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface, and a steam generator. The steam generator includes a heating element inside the tub, and a liquid level sensor on the outer surface of the tub, the liquid level sensor detecting a level of the liquid inside the tub, wherein the liquid level sensor includes a non-contacting sensor that detects the level of the liquid without directly contacting the liquid.

FIELD OF THE INVENTION

The present invention is directed toward a domestic household appliance, and more specifically, toward a steam generator for a domestic household appliance.

BACKGROUND OF THE INVENTION

A household appliance, such as a front-loading clothes washer, includes a housing having a door providing access to a washing unit in the interior of the appliance housing. The washing unit includes a watertight tub for holding washing/rinsing liquid. A cylindrical washing drum is rotatably mounted inside the tub. In operation, clothes or laundry are inserted into the washer through the door and placed in the rotating washing drum inside the tub. In a washing cycle, the household appliance wets the laundry to be washed with washing liquid and mechanically moves the laundry to release contaminants from the laundry. In a rinsing cycle, the household appliance wets the laundry to be rinsed with rinsing liquid and mechanically moves the laundry to release the residual washing liquid and contaminants from the laundry. A drive system rotates the washing drum inside the tub about an axis of the drum.

A heating element commonly is provided for heating the washing liquid or rinsing liquid in the tub of the washer to a desired temperature. The heating element may be disposed in a heater pocket or cavity formed in the bottom of the tub of the washer. In operation, the washing liquid flows into the heater pocket and over the heating element, such that heat is transferred from the heating element to the washing liquid, thereby raising the temperature of the washing liquid to the desired temperature.

A partial cross-sectional view of a conventional washer is illustrated in FIG. 6. The washer has drum 20 rotatably mounted in a tub 30. The tub 30 includes an integral heater pocket 40 formed in the bottom portion of the tub 30. The heater pocket 40 commonly has a first sidewall 42, a second sidewall 44 that is opposed to the first sidewall 42, and a third wall or bottom wall 46 connecting the first sidewall 42 to the second sidewall 44, thereby forming a cavity.

The heating element 50, which may include heater coils 52 and a base 56, is inserted into and sealingly engaged with an opening at a far end of the heater pocket 40, as viewed in FIG. 6. The heating element 50 can be, for example, a 1300 Watt heating element.

During the washing or rinsing cycle of the washer, the washing/rinsing liquid is supplied to the tub 30 for wetting the laundry to be washed. The volume of the washing/rinsing liquid supplied to the tub 30 is sufficient to fill the heater pocket 40 and to intrude at least into a lower portion of the drum 20 for wetting the laundry. In this manner, the level of the washing/rinsing liquid is above a lower portion of the outer cylindrical ring 22 of the drum 20 and the heater coils 52 are submerged under the washing liquid.

The heater pocket 40 may be in fluid communication with a drain assembly 60, which can include a discharge pump (not shown) and corrugated tubing (not shown) for discharging the washing liquid from the tub 30. During a draining cycle of the washer, the drain is opened and the washing/rinsing liquid drains from the drum 30 into the heater pocket 40, and then from the heater pocket 40 into the corrugated tubing of the drain assembly 60.

Some conventional washers provide a steam generating capability (e.g., steam cycle or function) that uses a completely separate and independent steam generator to generate steam to be supplied to the laundry. Commonly, the heat source is completely independent of the tub or the heating element of the tub. For example, some conventional washers provide a separate steam generator used to create steam that is then transferred and injected into the drum via a separate tube connecting the steam generator to the drum.

Some other conventional washers may include a steam generator or heating element that is inside the tub to generate steam for steam cleaning the laundry. These conventional washers may include several water level sensors or detectors that are positioned inside the tub between the heating element and the drum for detecting the level of the water in the tub.

For example, some conventional devices may include an analog pressure sensor that is positioned inside the tub to determine the water level inside the washer tub by pneumatic means. As illustrated in FIG. 6, other conventional devices may include, for example, at least three electrodes 111 that are positioned inside the tub 30 such that the water level can be confirmed by sending a signal to a controller (not shown) based on the electrical connection between the respective electrodes 111 when immersed in the water. Such conventional sensors 111 may include a single common electrode, a single low level confirmation electrode, and a single high level confirmation electrode, distal ends of which are provided with terminals exposed to the inner space of the tub 30. The terminal of the single high level confirmation electrode may be located higher than the heater, while the terminal of the single low level confirmation electrode may be located substantially at the same height as the terminal of the common electrode.

SUMMARY OF THE INVENTION

The present invention recognizes that it is desirable to provide a steam generating function while also minimizing additional parts and manufacturing costs. The present invention recognizes that important benefits, such as reducing costs, can be provided over the conventional devices by using the existing or “standard” heating element within the tub of the washer as the heat source for generating steam in the tub. The present invention also recognizes that there are difficult challenges associated with using the existing or “standard” heating element to generate steam in the tub.

For example, in a normal washing/rinsing cycle, the level of the washing/rinsing liquid in the tub may be permitted to rise high enough so that the washing/rinsing liquid intrudes into the rotating drum for wetting the laundry. In contrast, the laundry is not submerged in water during a steam mode or steam generating cycle using the heating element. In this case, the present invention recognizes that a level of the water supplied to the heater pocket for generating steam must be controlled such that the water level is low enough in the tub to prevent the water from contacting or intruding into the rotating drum, yet high enough to immerse the heating element in a sufficient mass of water for generating steam without exposing the heating element. The present invention recognizes that a distance between the heating element and the rotating drum in many conventional devices is small, and hence, the range of acceptable water levels is limited for achieving the desired steam generating function while preventing wetting of the laundry in the drum.

Conventionally, water level sensors have not been adequate to closely and accurately control the water level in such a limited and sensitive range. For example, some conventional devices may include an analog pressure sensor inside the tub to determine the water level inside the washer tub by pneumatic means. The present invention recognizes that such analog pressure sensors generally are not highly reliable devices for providing accurate and repeatable water levels, and hence, the conventional pressure sensors cannot maintain a reliable and accurate water level during a steam generation cycle.

Moreover, the present invention recognizes that the conventional sensors that are inside the tub necessarily are exposed to the washing/rinsing liquid, chemicals, contaminants, lint, etc. inside the tub, which may cause or increase the likelihood of sensor failures, sensor damage, sensor corrosion, etc., thereby reducing a lifespan of the sensors. Also, these conventional sensors commonly require the tub to be modified to include a penetration of the wall of the tub for attaching or inserting the sensor and/or transferring the signal from the sensor to a control unit outside the tub, which may affect the watertight characteristics of the tub and may increase the likelihood of water leaking from the tub. Furthermore, the conventional devices commonly require numerous parts and connections, for example, between the inside of the tub and the outside of the tub, thereby resulting in an increase in the number of parts, which in turn increases the material and assembly costs of the washer.

These problems and others are addressed by the present invention, a first exemplary embodiment of which comprises a washer including a housing having a door formed in a front panel thereof for accessing an interior of the housing, a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface, a drum rotatably mounted in the tub for receiving laundry through the door, the drum including a circumferential wall having an inner surface and an outer surface, the outer surface of the circumferential wall being adjacent to the inner surface of the tub, a steam generator, the steam generator including a heating element inside the tub and disposed between a lower portion of the outer surface of the circumferential wall of the drum and a lower portion of the inner surface of the tub, and a liquid level sensor on the outer surface of the tub, the liquid level sensor detecting a level of the liquid inside the tub.

Another exemplary embodiment of the invention comprises a household appliance including a housing having a door formed in a front panel thereof for accessing an interior of the housing, a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface, and a steam generator, the steam generator including a heating element inside the tub, and a liquid level sensor on the outer surface of the tub, the liquid level sensor detecting a level of the liquid inside the tub, wherein the liquid level sensor includes a non-contacting sensor that detects the level of the liquid without directly contacting the liquid.

A further exemplary embodiment of the invention comprises a household appliance including a housing having a door formed in a front panel thereof for accessing an interior of the housing, a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface, a steam generator, the steam generator including a heating element inside the tub, and liquid level sensor means on the outer surface of the tub, the liquid level sensor means for detecting a level of the liquid inside the tub, and a controller in communication with the heating element and the liquid level sensor means, the controller selectively controlling operation of the heating element for generating steam based on the level of the liquid detected by the liquid level sensor means.

The exemplary embodiments of the present invention provide a steam generator and a method of operating a steam generator that closely and accurately controls the water level for a steam mode or steam generating cycle using the existing or standard heating element of the washer, which also is used for heating the washing/rinsing liquid. In this manner, the exemplary embodiments of the present invention provide a secondary function for the existing heating element of a horizontal axis type washer (i.e., front-load washer).

The exemplary embodiments of the present invention use the heating element and preferably the heater pocket as a steam generation area. In operation, water is filled into the tub, and particularly into the heater pocket of the tub if so equipped, to a level that is sufficient to immerse the heating element in water but not high enough to intrude into the rotating drum. In order to facilitate the use the heating element and the heater pocket as a steam generator in a safe, reliable, and accurate manner, the exemplary embodiments of the present invention include a sensor that can accurately and reliably determine the water level relative to the position of the heating element in the tub and/or the bottom of the drum, etc. The sensor can be any type of sensor that can determine the physical level of the water using tactile, visual, capacitive, field effect or other means of directly and accurately detecting the actual water level. In a preferred embodiment, the sensor is a non-contacting or contactless sensor such as a thin film field effect or Hall effect sensor, a conductive level sensor, etc. These sensors can be off-the-shelf sensors, such as thin film field effect sensors.

In this manner, the exemplary embodiments of the present invention can utilize currently existing parts for a steam generator in a washer, thereby avoiding or eliminating a need to provide a separate steam generator or plumbing apparatus, which greatly simplifies the system. Moreover, the exemplary embodiments of the present invention can use the existing tub in a completely unmodified state, thereby greatly simplifying the implementation of a steam generator into various existing washer designs and types of washers. Furthermore, the exemplary embodiments of the present invention can minimize or reduce the number of additional parts for utilizing the unmodified tub and existing heating element and/or heater pocket as a steam generator, thereby minimizing or reducing manufacturing costs while providing the added valuable functions of a steam generating mode or cycle.

In an exemplary embodiment, the washer includes a thin film sensor, such as a field effect or Hall effect sensor, that is coupled to an outside of the tub and that can accurately detect a level of the water on the inside of the tub. The thin film field effect or Hall effect sensor on the exterior surface of the tub can detect the water level on the inside of the tub by sensing when the field surrounding the thin film field effect or Hall effect sensor is broken, interrupted, or altered by the washing/rinsing liquid inside the tub. In this manner, the exemplary embodiments can eliminate a penetration of the wall of the tub, thereby using the existing tub in a completely unmodified state and improving or maintaining the watertight characteristics of the tub. Moreover, since the sensor is coupled to the outer or exterior surface of the tub, the sensor is not exposed to the washing/rinsing liquid, chemicals, contaminants, lint, etc. inside the tub, which may prevent or reduce sensor failures, sensor damage, sensor corrosion, etc. and prolong the life of the sensor. Furthermore, the sensor can be easily and efficiently coupled to the outer or exterior surface of the tub, for example, by taping or pasting the thin film sensor to the outer surface of the tub, thereby minimizing or reducing assembly costs.

In an exemplary embodiment, a single thin film field effect or Hall sensor can be used to detect the level of washing/rinsing liquid inside the tub. For example, when the field of the thin film field effect sensor is broken, interrupted, or altered by the washing/rinsing liquid inside the tub, the sensor can detect a desired maximum level of the washing/rinsing liquid inside the tub. When the field of the thin film field effect sensor is not broken, interrupted, or altered by the washing/rinsing liquid inside the tub, the sensor can be used to detect a low level condition of the washing/rinsing liquid inside the tub.

In another exemplary embodiment, a plurality of thin film field effect sensors can be used to detect the level of washing/rinsing liquid inside the tub. For example, a first sensor can be coupled to the exterior surface of the tub at a location corresponding to a desired minimum level for the washing/rinsing liquid inside the tub, such as a level sufficient to immerse the heating element in the washing/rinsing liquid for generating steam without exposing the heating element. A second sensor can be coupled to the outer surface of the tub (i.e., surface mounted to the exterior of the tub) at a location corresponding to a desired maximum level for the washing/rinsing liquid inside the tub, such as a level that is lower than the bottom of the rotating drum for preventing wetting of the laundry in the rotating drum during the steam cleaning mode. In this manner, the plurality of sensors can be used to provide built-in hysteresis to maintain the level of the washing/rinsing liquid within a predetermined acceptable range for steam generation. The predetermined acceptable range can be easily adjusted by positioning or repositioning the sensors on the exterior of the tub.

The thin film field effect sensor can be positioned on a single side of the exterior of the tub for detecting the level of the washing/rinsing liquid inside the tub. In other embodiments, one or more additional thin film field effect sensors can be positioned on an opposite side of the exterior of the tub for detecting the level of the washing/rinsing liquid inside the tub. In this exemplary embodiment, one of the additional thin film field effect sensors can be co-planar with a thin film field effect sensor positioned on the opposite side of the exterior of the tub, for example, to provide redundancy, thereby further improving the accuracy, responsiveness, and/or safety of the system with a minimal increase in cost and assembly time.

The positioning of the thin film field effect is not limited to positions corresponding to the level of the washing/rinsing liquid for steam generation. In other exemplary embodiments, one or more thin film field effect sensors can be coupled to the exterior surface of the tub at a location corresponding to a desired maximum or minimum level for the washing/rinsing liquid inside the tub during a washing cycle, rinsing cycle, etc.

In other exemplary embodiments, the exterior surface or surfaces of the tub can include markings corresponding to the desired location or locations of one or more thin film field effect sensors to aid in the attachment and positioning of the sensors to the exterior of the tub, thereby further simplifying the assembly of the exemplary sensors on the structurally unmodified tub.

One of ordinary skill in the art will recognize that the present invention is not limited to sensing a level of washing/rinsing liquid in a washer. In other exemplary embodiments, the household appliance can include a steam oven, a dishwasher, etc.

In other exemplary embodiments, a thin film field effect sensor can be coupled to an exterior surface of a water tower, a chemical holding tank, a fuel holding tank, or the like in which it is desirable to accurately detect a level of a liquid inside a container, tub, or tank without modifying or penetrating the existing design of the container, tub, tank, etc.

Other features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of embodiments of the present invention will be better understood after a reading of the following detailed description, together with the attached drawings, wherein:

FIG. 1 is a front elevation view of a washer.

FIG. 2 is a cross-sectional schematic view of a washer according to an exemplary embodiment of the invention.

FIG. 3 is a partial cross-sectional schematic view of a steam generator according to an exemplary embodiment of the invention.

FIG. 4 is a partial cross-sectional schematic view of a steam generator according to an exemplary embodiment of the invention.

FIG. 5 is a partial cross-sectional schematic view of a steam generator according to an exemplary embodiment of the invention.

FIG. 6 is a partial cross-sectional schematic view of a conventional water level sensor of a washer.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION

The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Referring now to the drawings, FIGS. 1-5 illustrate exemplary embodiments of a household appliance having a steam generator. Wherever possible, the same reference numbers have been used throughout the drawings to refer to the same or like parts.

FIG. 1 illustrates a household appliance, such as a front-loading clothes washer 100, having a housing 10 and a door 12 to provide access to the interior of the appliance housing 10. The washer 100 wets the laundry to be washed with washing liquid and mechanically moves the laundry to release contaminants from the laundry.

With reference to FIGS. 1-5, the housing 10 encloses a washing unit, which includes a tub 30 having a rotating washing drum 20 that rotates or oscillates about an axis to move the laundry in the tub 30. The interior of the tub 30 is accessible through an opening, which corresponds to the door 12 of the housing 10, as illustrated in FIG. 1. In operation, a drive system (not shown) rotates or oscillates the rotating washing drum 20 within the tub 30. The drive system can include, for example, a motor, a pulley, and a drive belt (not shown).

As shown in FIGS. 2-5, the tub 30 can include a heater pocket 40 having a heating element 50 disposed therein. One of ordinary skill in the art will recognize that the heater pocket 40 may be a defined space or simply an area of the tub 30 that is under the rotating drum 20 and that accommodates the heating element 50. In the illustrated embodiments, a single heating element 50 is depicted. However, in other embodiments, a plurality of heating elements may be provided.

Referring again to FIGS. 3-5, the tub 30 can include a drain assembly 60 coupled to or formed in the bottom of the heater pocket 40 of the tub 30. The drain assembly 60 can include, for example, a discharge pump and corrugated tube (not shown) for discharging the washing/rinsing liquid from the tub 30. The heater pocket 40 can include a first sidewall 42, a second sidewall 44, and a bottom wall 46. The heating element 50 having heater coils 52 and a base 56 can be inserted into and sealingly engaged with an opening at the far end of the heater pocket 40, as viewed in FIG. 2. The heating element 400 can be, for example, a 300 Watt heating element.

With reference to FIGS. 2 and 3, an exemplary embodiment of the present invention will now be described.

The tub 30 has an inner surface 30A and an outer surface 30B. The drum 20 has a circumferential wall 22 having an inner surface 22A and an outer surface 22B. The outer surface 22B of the circumferential wall 22 is adjacent to the inner surface 30A of the tub 30. The heating element 50 is disposed in an area between a lower portion of the outer surface 22B of the circumferential wall 22 of the drum 20 and a lower portion of the inner surface 30A of the tub 30.

In the exemplary embodiment, a sensor 70 is positioned on the outer surface 30B of the tub 30, for example, on the sidewall 42 of the heater pocket 40 of the tub 30. The sensor 70 can detect a presence of a liquid on the inner surface 30A of the tub 30 that is opposed to the sensor 70. The sensor 70 can be, for example, any type of sensor that can determine the physical level of the water using tactile, visual, capacitive, field effect or other means of directly and accurately detecting the actual water level inside the tub 30 from outside the tub 30. In an exemplary embodiment, the sensor 70 is a non-contacting or contactless sensor such as a thin film field effect or Hall effect sensor, a conductive level sensor, etc. In a preferred exemplary embodiment, the sensor 70 is a thin film field effect or Hall effect sensor, and more particularly, an off-the-shelf thin film field effect or Hall effect sensor.

The sensor 70 can be coupled to the outer or exterior surface 30B of the tub 30, for example, by taping or pasting the thin film field effect sensor 70 to the outer surface 30B of the tub 30, or other suitable means for adhering or surface mounting the sensor 70 to the tub 30. The sensor 70 can be permanently fixed to the outer surface 30B of the tub 30 or removably secured to the outer surface 30B of the tub 30, for example using a re-usable adhesive, to allow for easy repositioning, maintenance, replacement, etc.

The sensor 70 can accurately detect a level of the washing/rinsing liquid on the inside of the tub 30. For example, the thin film field effect sensor 70 can be positioned and surface mounted on the outer surface 30B of the tub 30 to detect the water level on the inside surface 30A of the tub 30 by sensing when the field surrounding the thin film field effect sensor 70 is broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30. In this manner, the exemplary embodiments can eliminate a penetration of the wall of the tub 30, thereby using the existing tub 30 in a completely unmodified state and improving or maintaining the watertight characteristics of the tub 30. Moreover, since the sensor 70 is coupled to the outer surface 30B of the tub 30, the sensor 70 is not exposed to the washing/rinsing liquid, chemicals, contaminants, lint, etc. inside the tub 30.

In this exemplary embodiment, a single thin film field effect sensor 70 can be used to detect the level of washing/rinsing liquid inside the tub 30. For example, as illustrated in FIGS. 2 and 3, the sensor 70 can be coupled to the outer surface 30B of the tub 30 at a location corresponding to a desired level 80 for the washing/rinsing liquid inside the tub 30 for generating steam. The level 80 may be a horizontal plane extending through the area between the heating element 50 and the lower portion of the outer surface 22B of the circumferential wall 22 of the drum 20. The level 80 preferably is a predetermined amount higher than a level 90 of the coils 52 of the heating element 50 such that the coils 52 are immersed in a sufficient amount of washing/rinsing liquid for generating steam without exposing the coils 52 of the heating element 50, and preferably is a predetermined amount lower than a level 92 of the bottom of the outer surface 22B of the circumferential wall 22 of the rotating drum 20 for preventing wetting of the laundry in the rotating drum 20 during the steam cleaning mode.

In operation, the washing/rinsing liquid is filled into the tub 30 via a supply line 120, and particularly into the heater pocket 40 of the tub 30, to a level that is sufficient to immerse the heating element 50 in washing/rinsing liquid but not high enough to intrude into the rotating drum 20. When the field of the thin film field effect sensor 70 is broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30, the sensor 70 can detect a desired maximum level 80 of the washing/rinsing liquid inside the tub 30. A signal from the sensor 70 can be transmitted to a control unit 130 for controlling the supply of washing/rinsing liquid into the drum 30 and the supply of washing/rinsing liquid can be interrupted or stopped by closing a supply valve (not shown) to the supply line 120. The control unit 130 then can activate (i.e., turn on), or increase the temperature of, the heating element 50 to generate steam. As steam is generated, the level of the washing/rinsing liquid in the heater pocket 40 of the tub 30 may decrease. If, or when, the level of the washing/rinsing liquid drops below the level 80 of the sensor 70, the field of the thin film field effect sensor 70 will no longer be broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30. In this manner, the control unit 130 can use the sensor 70 to detect a low level condition of the washing/rinsing liquid inside the tub 30. The control unit 130 then selectively can supply additional washing/rinsing liquid to the tub 30 via the supply line 120 to increase the level of the washing/rinsing liquid until it again rises to the desired level 80. Additionally or alternatively, the control unit 130 selectively can deactivate (i.e., turn off), or reduce the temperature of, the heating element 50 when the low level condition is detected by the sensor 70, and then turn on or activate the sensor 70 again when the level rises back to the desired level 80.

With reference to FIG. 4, another exemplary embodiment of the present invention will now be described.

As shown in FIG. 4, the washer 100 can include a plurality of thin film field effect or Hall effect sensors 72, 74 coupled to the outer surface 30B of the tub 30 for detecting the level of washing/rinsing liquid inside the tub 30, and particularly, inside the heater pocket 40 of the tub 30. In this exemplary embodiment, a first sensor 72 can be coupled to the outer surface 30B of the tub 30 at a location substantially corresponding to a desired minimum level 82 for the washing/rinsing liquid inside the tub 30 for generating steam without exposing the coils 52 of the heating element 50. The level 82 preferably is a predetermined amount higher than a level 90 of the coils 52 of the heating element 50 such that the coils 52 are immersed in a sufficient amount of washing/rinsing liquid for generating steam without exposing the coils 52 of the heating element 50.

A second sensor 74 can be coupled to the outer surface 30B of the tub 30 at a location corresponding to a desired maximum level 84 for the washing/rinsing liquid inside the tub 30 for preventing wetting of the laundry in the rotating drum 20 during the steam cleaning mode. The level 84 preferably is a predetermined amount lower than the bottom of the outer surface 22B of the circumferential wall 22 of the rotating drum 20 for preventing wetting of the laundry in the rotating drum 20 during the steam cleaning mode.

In this manner, a plurality of sensors 72, 74 can be used to maintain the level of the washing/rinsing liquid within a predetermined acceptable range for steam generation, for example, such that the coils 52 are immersed in a sufficient amount of washing/rinsing liquid for generating steam without exposing the coils 52 of the heating element 50 while preventing wetting of the laundry in the rotating drum 20 during the steam cleaning mode. The predetermined acceptable range can be easily adjusted by positioning or repositioning the sensors 72, 74 on the outer surface 30B of the tub 30.

In operation, the washing/rinsing liquid is filled into the tub 30, and particularly into the heater pocket 40 of the tub 30 via the supply line 120 (shown in FIG. 2), to a level that is sufficient to immerse the heating element 50 in washing/rinsing liquid but not high enough to intrude into the rotating drum 20. When the field of the thin film field effect sensor 72 is broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30, the sensor 72 can detect a desired minimum level 82 of the washing/rinsing liquid inside the tub 30. A signal from the sensor 72 can be transmitted to a control unit 130 (shown in FIG. 2) for selectively controlling the supply of washing/rinsing liquid into the drum 30. The control unit 130 selectively can continue the supply of washing/rinsing liquid by turning on or off a supply valve (not shown) to the supply line 120, while selectively activating the heating element 50 to generate steam.

If, or when, the field of the thin film field effect sensor 74 is broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30, the sensor 74 can detect a desired maximum level 84 of the washing/rinsing liquid inside the tub 30. A signal from the sensor 74 can be transmitted to the control unit 130 (shown in FIG. 2) for selectively controlling the supply of washing/rinsing liquid into the drum 30 and the control unit 130 selectively can interrupt or stop the supply of washing/rinsing liquid into the tub 30. The control unit 130 selectively can continue to operate the heating element 40 to generate steam.

As steam is generated, the level of the washing/rinsing liquid in the heater pocket 40 of the tub 30 may decrease. If, or when, the level of the washing/rinsing liquid drops below the level 82 of the sensor 72, the field of the thin film field effect sensor 72 will no longer be broken, interrupted, or altered by the washing/rinsing liquid inside the tub 30. Thus, the sensor 72 can be used to detect a low level condition of the washing/rinsing liquid inside the tub 30 and additional washing/rinsing liquid can be supplied to the tub 30 via the supply line 120 (shown in FIG. 2) to increase the level of the washing/rinsing liquid until it again rises to a desired level that is equal to or greater than level 82 and equal to or less than level 84. Additionally or alternatively, the heating element 50 selectively can be turned off when the low level condition is detected by the sensor 72, and then selectively turned on again when the level rises to or above the desired level 82.

As shown in FIG. 5, the positioning of the thin film field effect sensors 70, 72, and 74 is not limited to positions corresponding to the level of the washing/rinsing liquid for steam generation. In other exemplary embodiments, one or more additional thin film field effect sensors 76 can be coupled to the outer surface 30B of the tub 30 at one or more locations corresponding to, for example, a desired maximum or minimum level 86 for the washing/rinsing liquid inside the tub 30 for wetting the laundry inside the drum 20 during a washing cycle, rinsing cycle, etc.

With reference again to FIGS. 2-5, the thin film field effect sensors 70, 72, 74, and/or 76 can be positioned on a single side of the outer surface 30 B of the tub 30 for detecting the level of the washing/rinsing liquid inside the tub 30. In other embodiments, one or more sensors 70, 72, 74, and/or 76 can be positioned on opposite sides of the tub 30.

As shown in FIG. 2, another exemplary embodiment can include one or more additional or optional thin film field effect sensors, such as a sensor 70A. The additional sensor 70A can be positioned on the outer surface 30B of the tub 30 on an opposite side of the tub 30 from the sensor 70 for detecting the level of the washing/rinsing liquid inside the tub 30. In this exemplary embodiment, the additional thin film field effect sensor 70A can be co-planar with the thin film field effect sensor 70 positioned on the opposite side of the outer surface 30B of the tub 30, for example, to provide redundancy, thereby further improving the accuracy, responsiveness, and/or safety of the system with a minimal increase in cost and assembly time. Additional sensors can be provided to provide redundancy for one or more of sensors 70, 72, 74, and/or 76.

In other exemplary embodiments, the outer surface 30B of the tub 30 can include markings (not shown) corresponding to the desired location or locations of one or more thin film field effect sensors (e.g., 70, 72, 74, and/or 76) to aid in the attachment and positioning of these sensors to the outer surface 30B of the tub 30, thereby further simplifying the assembly of the exemplary sensors with a structurally unmodified tub.

To summarize, according to a disclosed exemplary embodiment, a household appliance, and more particularly a washer, is provided. The exemplary household appliance includes a housing 10 having a door 12 formed in a front panel thereof for accessing an interior of the housing 10. A tub 30 is disposed inside the housing 10 for containing a liquid. The tub 30 has an inner surface 30A and an outer surface 30B. A drum 20 is rotatably mounted in the tub 30 for receiving laundry through the door 12. The drum 20 includes a circumferential wall 22 having an inner surface 22A and an outer surface 22B, the outer surface 22B of the circumferential wall 22 being adjacent to the inner surface 30A of the tub 30. A steam generator includes a heating element 40 inside the tub 30 and disposed between a lower portion of the outer surface 22B of the circumferential wall 22 of the drum 20 and a lower portion of the inner surface 30A of the tub 30, and a liquid level sensor (e.g., 70, 72, 74, and/or 76) on the outer surface 30B of the tub 30, the liquid level sensor (e.g., 70, 72, 74, and/or 76) detecting a level (e.g., 80, 82, 84, and/or 86) of the liquid inside the tub 30. The liquid level sensor can be, for example, a sensor that determines the physical level of the water using tactile, visual, capacitive, field effect or other means of directly and accurately detecting the actual water level. The liquid level sensor can be a non-contacting or contactless sensor such as a thin film field effect or Hall effect sensor, a conductive level sensor, etc. These sensors can be off-the-shelf sensors, such as an off-the-shelf thin film field effect sensor.

Another exemplary embodiment of the invention comprises a household appliance 100 including a housing 10 having a door 12 formed in a front panel thereof for accessing an interior of the housing 10. A tub 30 is disposed inside the housing 10 for containing a liquid. The tub 30 has an inner surface 30A and an outer surface 30B. A steam generator includes a heating element 40 inside the tub 30 and a liquid level sensor (e.g., 70, 72, 74, and/or 76) on the outer surface 30B of the tub 30, the liquid level sensor (e.g., 70, 72, 74, and/or 76) detecting a level (e.g., 80, 82, 84, and/or 86) of the liquid inside the tub 30. The liquid level sensor (e.g., 70, 72, 74, and/or 76) includes a non-contacting sensor (e.g., 70, 72, 74, and/or 76) that detects the level of the liquid without directly contacting the liquid.

A further exemplary embodiment of the invention comprises a household appliance 100 including a housing 10 having a door 12 formed in a front panel thereof for accessing an interior of the housing 10. A tub 30 is disposed inside the housing 10 for containing a liquid. The tub 30 has an inner surface 30A and an outer surface 30B. A steam generator includes a heating element 40 inside the tub 30 and liquid level sensor means (e.g., 70, 72, 74, and/or 76) on the outer surface 30B of the tub 30, the liquid level sensor means (e.g., 70, 72, 74, and/or 76) for detecting a level of the liquid inside the tub 30. A controller 130 is in communication with the heating element 40 and the liquid level sensor means (e.g., 70, 72, 74, and/or 76). The controller 130 selectively controls the operation (e.g., turning on and off, or increasing and decreasing the temperature) of the heating element 40 for generating steam based on the level of the liquid detected by the liquid level sensor means (e.g., 70, 72, 74, and/or 76).

This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

For example, another exemplary embodiment is directed to a device and method of sensing a level of washing/rinsing liquid in a dishwasher. In this embodiment, one or more thin film field effect sensors can be coupled to an outer surface of a washing chamber to detect a level of washing/rinsing liquid inside the washing chamber.

Another exemplary embodiment is directed to a device and method of sensing a level of water in a steam oven. In this embodiment, one or more thin film field effect sensors can be coupled to an outer surface of a cooking chamber to detect a level of water inside the cooking chamber.

Other exemplary embodiments are directed to a device and method of sensing a level of water in a water tower, a chemical holding tank, a fuel holding tank, or the like. In these embodiments, one or more thin film field effect sensors can be coupled to an outer surface of the water tower, chemical holding tank, fuel holding tank, or the like to detect a level of liquid (e.g., water, chemicals, fuel, etc.) inside the water tower, chemical holding tank, fuel holding tank, or the like.

The present invention has been described herein in terms of several preferred embodiments. However, modifications and additions to these embodiments will become apparent to those of ordinary skill in the art upon a reading of the foregoing description. It is intended that all such modifications and additions comprise a part of the present invention to the extent that they fall within the scope of the several claims appended hereto.

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”

It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly. 

1. A washer comprising: a housing having a door formed in a front panel thereof for accessing an interior of the housing; a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface; a drum rotatably mounted in the tub for receiving laundry through the door, the drum including a circumferential wall having an inner surface and an outer surface, the outer surface of the circumferential wall being adjacent to the inner surface of the tub; and a steam generator that generates steam from the liquid in the tub, the steam generator including: a heating element inside the tub and disposed between a lower portion of the outer surface of the circumferential wall of the drum and a lower portion of the inner surface of the tub; and a liquid level sensor on the outer surface of the tub, the liquid level sensor detecting a level of the liquid inside the tub.
 2. The washer of claim 1, wherein the liquid level sensor is disposed entirely on the outer surface of the tub.
 3. The washer of claim 1, wherein the liquid level sensor includes a thin film sensor.
 4. The washer of claim 1, wherein the liquid level sensor includes a field effect sensor.
 5. The washer of claim 1, wherein the liquid level sensor includes a non-contacting sensor that detects the level of the liquid without directly contacting the liquid.
 6. The washer of claim 1, comprising: a controller in communication with the heating element and the liquid level sensor, the controller selectively controlling operation of the heating element for generating steam based on the level of the liquid detected by the liquid level sensor.
 7. The washer of claim 6, comprising: a liquid supply unit that supplies the liquid to the tub; wherein the controller is in communication with the liquid supply unit, the heating element, and the liquid level sensor, the controller selectively controlling operation of the liquid supply unit and the heating element based on the level of the liquid detected by the liquid level sensor.
 8. The washer of claim 1, comprising: a liquid supply unit that supplies the liquid to the tub; a controller in communication with the liquid supply unit and the liquid level sensor, the controller selectively controlling operation of the liquid supply unit based on the level of the liquid detected by the liquid level sensor.
 9. The washer of claim 1, wherein the liquid level sensor includes: a first liquid level sensor on the outer surface of the tub, wherein the first liquid level sensor detects a presence of the liquid on the inner surface of the tub that is opposed to the first liquid level sensor.
 10. The washer of claim 9, wherein the liquid level sensor includes: a second liquid level sensor on the outer surface of the tub, wherein the second liquid level sensor detects a presence of the liquid on the inner surface of the tub that is opposed to the second liquid level sensor.
 11. The washer of claim 10, wherein the liquid level sensor includes: a third liquid level sensor on the outer surface of the tub, wherein the third liquid level sensor detects a presence of the liquid on the inner surface of the tub that is opposed to the third liquid level sensor.
 12. The washer of claim 9, wherein the first liquid level sensor is disposed at a first location on the outer surface of the tub in a horizontal plane extending through an area between the heating element and the lower portion of the outer surface of the circumferential wall of the drum.
 13. The washer of claim 12, wherein the first location of the first liquid level sensor on the outer surface of the tub corresponds to a predetermined level of the liquid inside the tub for generating steam using the heating element.
 14. The washer of claim 12, wherein the first location of the first liquid level sensor on the outer surface of the tub corresponds to a predetermined maximum level of the liquid inside the tub for generating steam using the heating element.
 15. The washer of claim 12, wherein the first location of the first liquid level sensor on the outer surface of the tub corresponds to a predetermined minimum level of the liquid inside the tub for generating steam using the heating element.
 16. The washer of claim 9, wherein the first liquid level sensor is disposed at a location on the outer surface of the tub in a horizontal plane extending through an area above the lower portion of the outer surface of the circumferential wall of the drum.
 17. The washer of claim 10, wherein the first liquid level sensor is disposed at a first location on the outer surface of the tub in a horizontal plane extending through an area between the heating element and the lower portion of the outer surface of the circumferential wall of the drum, wherein the second liquid level sensor is disposed at a second location on the outer surface of the tub in a second horizontal plane extending through the area between the heating element and the lower portion of the outer surface of the circumferential wall of the drum, and wherein the second horizontal plane is one of above and below the first horizontal plane.
 18. The washer of claim 17, wherein one of the first horizontal plane and the second horizontal plane corresponds to a predetermined maximum level of the liquid inside the tub for generating steam using the heating element, and wherein another of the first horizontal plane and the second horizontal plane corresponds to a predetermined minimum level of the liquid inside the tub for generating steam using the heating element.
 19. The washer of claim 11, wherein the first liquid level sensor is disposed at a first location on the outer surface of the tub in a horizontal plane extending through an area between the heating element and the lower portion of the outer surface of the circumferential wall of the drum, wherein the second liquid level sensor is disposed at a second location on the outer surface of the tub in a second horizontal plane extending through the area between the heating element and the lower portion of the outer surface of the circumferential wall of the drum, wherein the second horizontal plane is one of above and below the first horizontal plane, and wherein the third liquid level sensor is disposed at a third location on the outer surface of the tub in a third horizontal plane extending through an area above the lower portion of the outer surface of the circumferential wall of the drum.
 20. The washer of claim 10, wherein the second liquid level sensor is disposed at a second location on the outer surface of the tub on an opposite side of the tub from the location of the first liquid level sensor and substantially in a same horizontal plane as the first liquid level sensor.
 21. The washer of claim 1, wherein the tub includes: a heater pocket formed in the lower portion of the inner surface of the tub, wherein the heating element is disposed in the heater pocket.
 22. The washer of claim 10, wherein the first liquid level sensor and the second liquid level sensor each include a surface mounted field effect sensor.
 23. The washer of claim 11, wherein the first liquid level sensor, the second liquid level sensor, and the third liquid level sensor each include a surface mounted field effect sensor.
 24. A household appliance comprising: a housing having a door formed in a front panel thereof for accessing an interior of the housing; a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface; and a steam generator that generates steam from the liquid in the tub, the steam generator including: a heating element inside the tub; and a liquid level sensor on the outer surface of the tub, the liquid level sensor detecting a level of the liquid inside the tub, wherein the liquid level sensor includes a non-contacting sensor that detects the level of the liquid without directly contacting the liquid.
 25. The household appliance of claim 24, wherein the liquid level sensor includes a field effect sensor.
 26. The household appliance of claim 24, comprising: a controller in communication with the heating element and the liquid level sensor, the controller selectively controlling operation of the heating element for generating steam based on the level of the liquid detected by the liquid level sensor.
 27. The household appliance of claim 26, comprising: a liquid supply unit that supplies the liquid to the tub; wherein the controller is in communication with the liquid supply unit, the heating element, and the liquid level sensor, the controller selectively controlling operation of the liquid supply unit and the heating element based on the level of the liquid detected by the liquid level sensor.
 28. The household appliance of claim 24, comprising: a liquid supply unit that supplies the liquid to the tub; a controller in communication with the liquid supply unit and the liquid level sensor, the controller selectively controlling operation of the liquid supply unit based on the level of the liquid detected by the liquid level sensor.
 29. The household appliance of claim 24, wherein the liquid level sensor is disposed at a location on the outer surface of the tub corresponding to one of a predetermined level, a predetermined maximum level, and a predetermined minimum level of the liquid inside the tub for generating steam using the heating element.
 30. The household appliance of claim 24, wherein the liquid level sensor includes: a plurality of liquid level sensors on the outer surface of the tub, wherein each of the plurality of liquid level sensors respectively detects a presence of the liquid on the inner surface of the tub that is opposed to each of the plurality of liquid level sensors.
 31. The household appliance of claim 30, wherein a first liquid level sensor of the plurality of liquid level sensors is disposed at a first location on the outer surface of the tub corresponding to a predetermined maximum level of the liquid inside the tub for generating steam using the heating element, and wherein a second liquid level sensor of the plurality of liquid level sensors is disposed at a second location on the outer surface of the tub corresponding to a predetermined minimum level of the liquid inside the tub for generating steam using the heating element.
 32. A household appliance comprising: a housing having a door formed in a front panel thereof for accessing an interior of the housing; a tub disposed inside the housing for containing a liquid, the tub having an inner surface and an outer surface; a steam generator that generates steam from the liquid in the tub, the steam generator including: a heating element inside the tub; and liquid level sensor means on the outer surface of the tub, the liquid level sensor means for detecting a level of the liquid inside the tub; and a controller in communication with the heating element and the liquid level sensor means, the controller selectively controlling operation of the heating element for generating steam based on the level of the liquid detected by the liquid level sensor means.
 33. The household appliance of claim 32, comprising: a liquid supply unit that supplies the liquid to the tub; wherein the controller is in communication with the liquid supply unit, the heating element, and the liquid level sensor means, the controller selectively controlling operation of the liquid supply unit and the heating element based on the level of the liquid detected by the liquid level sensor means. 